1. Field of the Invention
Novel halogenated organoaluminum catalysts are prepared by prereacting a material of the formula: EQU R.sub.m AlX.sub.3-m
wherein m is an integer of from 1 to 3 inclusive, R is the same or different alkyl radical of straight or branched chain structure of from 1 to 7 carbons and X is the same or different halogen selected from the group consisting of chlorine and bromine with Y moles of halogen or mixed halogen per mole of aluminum compound wherein the halogen is selected from the group consisting of chlorine and bromine such that (m-Y) is less than 0.7 to about 0.2. The materials must be prepared sufficiently prior to use to insure extensive reaction of the components to yield an effective polymerization catalyst. Preferably, the components are prereacted for at least 2 minutes, more preferably at least 10 minutes, most preferably at least 4 hours, i.e. (overnight). The catalyst is prepared at any temperature insuring liquid conditions, i.e., -100.degree..fwdarw.+100.degree. C. depending on the components selected for reaction, ambient temperature being most convenient.
The compounds are useful as hydrocarbon soluble catalysts and are prepared sufficiently in advance of use to insure complete reaction between the two components yielding the reactive entity. The novel soluble catalysts frequently exhibit higher catalytic activity and efficiency than those of the prior art. They permit polymerization reactions to be run which yield higher molecular weight polymers and copolymers at higher temperatures. The catalysts of the instant invention are particularly useful in the synthesis of highly unsaturated isoolefin multiolefin copolymers of high molecular weight.
2. Description of the Prior Art
Aluminum compounds are widely used as polymerization catalysts. Aluminum chloride is commonly used to initiate cationic polymerizations but it has the disadvantage of little or no solubility in many desirable hydrocarbon systems especially where homogeneous polymerizations are required. Aluminum bromide which is soluble in hydrocarbons, has limited utility as such in a number of desirable systems. Alkylaluminum dihalides are generally less reactive than the aluminum halides but offer the advantage of excellent hydrocarbon solubility. To enhance their reactivity, they are frequently used together with cocatalysts. Proton donators like the halogen acids, are placed in the polymerization medium and are said to be ionized by the aluminum compound thereby releasing protons to initiate polymerization. Halogens and organic halogen compounds are also ionized in situ to initiate cationic polymerization. In the case of dialkylaluminum halides and aluminum alkyls, such cocatalysts are required since these compounds are not generally active in themselves. Also compounds like dialkylaluminum iodides and alkylaluminum diodides, which are generally not effective initiators in and of themselves, have been utilized with halogen cocatalysts, such as iodine, to initiate the polymerization. The iodine must be present in the polymerization medium and is ionized by the aluminum component, the ions initiating the polymerization. This is a good illustration of cocatalysis since neither the starting alkylaluminum iodides nor the product aluminum iodide is a catalyst by itself so the cocatalyst must be present in the polymerization medium.
The catalyst systems of the instant invention differ markedly from those of the prior art. The halogens, and interhalogen compounds are not used as cocatalysts but instead are prereacted with the organic aluminum compound to generate novel catalyst species which are hydrocarbon soluble and can be utilized in hydrocarbon polymerization systems. These catalysts are generally more reactive and give higher molecular weights than the corresponding organoaluminum compounds from which they are derived. Furthermore, the prereacted catalysts of the instant invention give products superior to the polymerization products obtained using halogens or interhalogen compounds as cocatalysts.
Numerous prior art examples using cocatalysts are extant. These are clearly distinguishable from the catalysts of the instant invention. The halides, etc. of the prior art are used either in situ as cocatalysts or as complexing agents.
U.S. Pat. No. 2,220,930 teaches the manufacture of polymers using catalysts such as dialkylaluminum halides or alkylaluminum halides, generally represented as MX.sub.m R.sub.n where M represents aluminum, gallium or boron, X represents halogen, R represents a monovalent hydrocarbon radical, m or n represent integers 1 to 2 l inclusive, and m+n=3. The catalyst can also be a complex of the above compounds with inorganic halides (e.g. NaCl) or with ammonia or amines. In practice, U.S. Pat. No. 2,220,930 utilized either dialkylaluminum halides or alkylaluminum dihalides alone or in a mixture of equal parts which is commonly known as the sesquihalide. The polymers of isobutylenes obtained were low molecular weight resins.
U.S. Pat. No. 2,387,517 relates to the manufacture of polymers prepared by the copolymerization of various unsaturated compounds in the presence of catalysts of the type MX.sub.m R.sub.n where M represents aluminum, gallium or boron, X represents a halogen, R represents a monovalent hydrocarbon radical, m or n represent integers from 1 to 2 inclusive and m+n=3. The invention is particularly directed to the formation of curable rubber-like products by the copolymerization of isobutylene with low molecular weight diolefins, especially those having 4 to 6 carbon atoms. The products are described as ranging in molecular weight from 1000 to 3000 up to 300,000 or higher. However, the type of molecular weight is not indicated (i.e. number average, weight average) nor is an actual polymer approaching 300,000 molecular weight prepared. The composition used as catalysts in the above two related cases are not prepared by prereacting an alkyl aluminum halide with halogens, halogen acid or interhalogen compounds of the instant invention and do not suggest the superiority which the instant compositions demonstrate as catalysts.
U.S. Pat. No. 2,388,428 relates to an improved method for effecting organic chemical reactions by generating Friedel-Crafts metal halide catalysts in situ. It teaches dissolving an organo aluminum compound in a hydrocarbon reactant being charged to the process and contacting said solution with an excess of hydrogen halide in a reaction zone under hydrocarbon conversion conditions whereby an aluminum halide catalyst is generated in situ and the conversion reaction is effected. The hydrogen halide is added in excess (in an excess over the amount required to completely convert the organoaluminum compound to the aluminum halide so as to generate aluminum halide (e.g. AlCl.sub.3) in situ). Such generation of aluminum chloride is described as being subject to greater control and of greater precision than prior art methods of dissolving or suspending the aluminum halide in the reaction mixture. Particular note should be taken of the fact that the catalyst components are not prereacted and then added to the reaction zone, but are reacted in situ. Furthermore, the stoichiometry is quite different from the catalysts of the instant invention. The use of the catalyst of U.S. Pat. No. 2,388,428 for the purposes of polymerization is not taught as the examples are directed solely to isomerization and alkylation.
U.S. Pat. No. 3,349,065 teaches an improved catalyst system for producing high molecular weight butyl rubbers. The catalyst system comprises a dialkylaluminum halide together with a small but critical amount of an anhydrous hydrogen halide as a promoter (cocatalyst). The amount of anhydrous hydrogen halides used ranges from 0.001 mole to 0.05 mole promoter per mole of dialkylaluminum monohalide. The maximum desirable ratio is 0.05 mole promoter per mole of catalyst. This is clearly outside the range of the catalyst of the instant invention. Furthermore, the hydrogen halide is added to a solution containing both the dialkylaluminum chloride and monomer and is not prereacted with said organoaluminum compound as in the method of the instant invention.
U.S. Pat. No. 3,562,804 also describes the use of an organoaluminum compound in conjunction with hydrogen chloride or a C.sub.3 -C.sub.7 organic halide compound as promoter to produce low viscosity mastic compositions. Here again, the catalyst and promoter were combined in the presence of monomer and all examples teach the separate addition of catalyst and promoter to the polymerization (monomer) mixture.
U.S. Pat. No. 3,850,897 teaches a procedure of the production of polymers and copolymers of isobutylene. The catalyst disclosed is of the general formula RAl(YR')X where Y is an oxygen or sulfur atom together with a wide variety of promoters. The aluminum compounds disclosed in this patent are different from those of the instant invention. Furthermore, the patent in question teaches the necessity of combining catalyst and cocatalyst in the presence of monomers. Stepwise addition of catalyst and cocatalyst to the polymerization medium is demonstrated in the examples.
U.S. Pat. No. 3,835,079 teaches hot melt compositions comprising styrene, isobutylene copolymer wax and a primary resin. The catalysts employed a system utilizing a primary component alkylaluminum dihalide with a promoter (cocatalyst) such as hydrogen halide. The maximum cocatalyst is 30 mole percent of the primary catalyst. A more limited range, 2.5 to 15 is preferred or 5 to 10% with cocatalysts such as water. The range of compositions is clearly outside that of the instant invention. Furthermore, the promoters are stated to be cocatalysts in this patent while they are consumed in a prior reaction in the instant invention and are not available to serve as cocatalysts.
U.S. Pat. No. 3,560,458 teaches a polymerization process utilizing a catalyst of the type Al(M).sub.2 R where M is an alkyl group and R is alkyl, hydrogen or halogen. It is obvious that the catalyst intended for use is the alkyl or the monohalide. Experimental procedure reveals a stepwise addition of cocatalyst promoters to a solution containing catalyst in the cationically polymerizable monomer.
British Pat. No. 1,362,295 teaches a catalyst suitable for use in the polymerization of unsaturated compounds and a process for employing such a catalyst. The catalyst used is a two-component substance, the primary component being R.sub.2 AlX wherein R is a hydrocarbon or hydrogen radical, X can be hydrocarbon, hydrogen or halogen. The secondary component is represented as YZ wherein each of Y and Z are the same or different halogen. The component can be present in a ratio of primary to secondary of from 0.1:1 to 1000:1.
U.S. Pat. No. 3,757,000 to Scardiglia teaches the use of ethyl aluminum dichloride as catalyst mixed with a cocatalyst selected from the group of water, alcohols, alkyl halides and HCl which is non-applicable to the instant application.